Electromechanical timer



18 1959 1.. E. RICHTMYER ETAL 2,900,021

ELECTROMECHANICAL TIMER Filed May 10, 1955 INVENTORS Lawson E R/chfmyer Paul 6. Gert/70rd 32 7 F wmizmw 25 i g- L 3 8 M Mad ATTORNEYS ELECTROMECHANICAL .TIMER Gerhard, -Palmerton;'Pa assignormto'the United-States 5.0fAl1181'i6fi .as;represented ebyedhe :Secretary of the :Army

A. ttlimioirMay"1L0; 1 5 ."searNqssor ia v reclaim. :(Cl.':-1=61-+=1) (Gr nted underfTitlei 35,;Us. Code. (1952),.sec. .266)

The. invention-.described -lrerein may be manufactured :andaused by or .for --.the Government I for; governmental ,purposes -without the payment .to us of Qany royalty ,thereon.

This invention relates to;timers.and particularly to an electromechanical timer.

; One object of :this invention isanew and novel variable 1 speed; electromechanical timer.

.Another' object -is-a IlW; and novel-;escapement means for: an: electromechanical timer.

.Anotherobject isarnew and novel method of varying the-speed. of aneelectrornechanical timer.

A further object is a self-energizing timer adaptable for prolonged-operation.

The specificnatureof. the .inventionaswell as other objects and advantages thereof will clearly appear from the; following description and;;drawing wherein:

figure ,1 is a schematic mechanical diagram :of the invention.

:Figure .2 :is an enlarged. Schematic diagramcof ,the escapernent and escapement actuating means, at jthethalf "cycle position. 7

:Figure 3 ,'is a view similar to E-ig.-.1- whereinithe cscape- 'rment ,is-at=a position beyond the halfscycle position.

sFigure -4 isia schematic; diagrarnofthe electrical system Jot-the invention,

.A preferred embodiment of.-the -inventiontcombines :a :novel mechanical escapernent andescapement: actuating means- Refe ng o. Bi 1., th escap whee 1101's provided with a plurality of beveled teeth indicated generally by numeral 11, the teeth being equally spaced about the periphery. of the wheel as at 11a, 11b, 110, etc. The teeth are beveled in the direction of travel of the Wheel, counterclockwise as seen in the drawing. The oscillating pallet member 12 of the escapement has a pair of pallet pins 13a and 13b adapted to cooperate with the teeth 11 of wheel 10. These pallet pins are located upon member 12 in a particular relationship to pivot 14 and teeth 11 in a manner described hereinafter. Arm 15 depends from member 12.

Wheel is a part of a gear train indicated generally by numeral 16. Pinion 17 of gear train 16, which is adapted to rotate with wheel 10, engages gear 18. Pinion 19, which turns with gear 18, engages gear 20. Pinion 21, which turns with gear 20, engages gear 22. And pinion 23, which turns with gear 22 engages gear 24. Gear 20 and pinion 21 are stripped of somewhat less than. half of their teeth. The remaining teeth of each member are located on diametrically opposite sides of the combined gear and pinion.

Spiral spring 25 biases gear 24 in the counterclockwise direction, gear 24 adapted to drive the remainder of gear train 16. Gear 24 has arm 26 affixed thereto, said arm adapted to actuate switch lever 27 to cause the lever to move to position 27a in contact with terminal 2 8, thus, closing an electrical circuit, not shown. Electric leads 29 connect lever 27 and terminal 28 with the circuit to be ,and attracts armature-38 thereto. vacts againstrarmJS of rpallet member 12'to cause the 'member to rotate. counterclockwise aafew. degrees about pivot 14.

2,900,021 Patented Aug. 18, 1959 closed. tTorsionspring 30 urges lever .27 to'move clockwise to its functioned position shown at 27a. Grounded leafspring. 3,1 normally. restrains switch lever v27 from moving to its functioned position.

- Numeral .32 indicates an electromagnet which is connectedelectricallywithan energizing unit such as relaxation oscillator 33, the components i It is understood that other electromechanical transof which are shown in .ducerswsuchrasg piezoelectric means can be employed in lieu of the-electromagnet.

The energizer which comprisesv a battery 34, Fig. 4, has a cur-rent limiting :devicesuch as a rheostat, constant current ionchamber, or variable resistor'35 in series therewith. vA capacitor'36 is connected across the battery :and. resistor, anda diode 37 and electromagnet 32 are connected in series and.a1'e placed inparallel with. the capacitor. -'Norma'lly, a variable current limiting device and a variable capacitor are employed.

-A magnetically-sensitive armature '38, pivoted at 39, is adapted toaact against arm 15 of :pallet member 12 as the armature rotates clockwise under the attraction of electromagnet 32.

Depending upon the parameters of the various circuit elements in Fig.4, capacitor 36-will be charged by battery .34 through -resistor:-35 .and" then discharged through diode Y 37 and. electromagnet .32--ata. predetermined. repetitive rate. At each:discharge,; electromagnet 32 is energized Armature 38, in turn,

1 Escape wheel Ill-is :drivenby spring. 25'. through gear ...train -.16.- so. that, whcn:arm-15:is.moved by armature 38 wheel 10: advances adistance equalato thenthickness of one tooth. Theretofore, whee1.-10 -had been restrained :by the rengagement of-tooth ,ll-baand pallet-pin 13a.

Almost,-.irnrnediately,the beveled; portion of tooth 11d moves-relative-to palletpin13b,'tpallet member .12 is tooth 11a with pallet pin 13a. The escapement then awaits another pulse from electromagnet 32, at which time the cycle is repeated.

It will be noted that pallet pin 13a is so located with respect to pivot 14 as to engage the leading edge of a tooth 11 and to thereby lock the escapement against further movement. Pallet pin 13b is located with respect to pivot 14 so that any tooth 11 tends to rotate the pallet member 12 in a clockwise direction to urge pin 13a to follow a direction toward the root circle of wheel 10 to ultimately be engaged by a tooth 11. The principal element tending to rotate pallet member 12 counterclockwise is armature 38.

Each time capacitor 36 discharges, escape wheel 10 advances a distance equal to the distance between the leading edges of two adjacent teeth. The system can be adjusted to obtain a rapid repetitive rate such as one discharge per second, a slow repetitive rate such as one discharge per month, or any other repetitive rate by adjusting resistor 35 and/or capacitor 36, the only limitation being the capabilities of presently available electrical components. Thus means are provided for regulating the rotational speed of the escape wheel at variable rates.

Once in operation, the system continues to function until the teeth of gear 20 run out with respect to pinion 19. Almost immediately thereafter, the teeth of pinion 21 run out with respect to gear 22. At that point the escapement has no more im iuence on the speed of rotation of gear 24. Gears 22 and 24 spin without restraint under the urging of spring 25. Arm 26 engages switch lever 27 causing the lever to move in the clockwise direction beyond the influence of leaf spring 31. Spring 30 takes over thereafter to move lever 27 to position 27a in contact with terminal 28, closing the electrical circuit, not shown.

It will be understood that the spring energy consumed in driving gear train 16 to the functional position is only a small fraction of the spring energy available. The remainder is available for doing work such as moving a weight or linkage.

It will be understood also that the electromechanical timer is, in essence, a digital counter, the total elapsed time from initiation to function of the timer being the number of counts multiplied by the time lapse between counts. Inasmuch as one count is equal to one pulse of the electromagnet, the timer can be preset or advanced any desired amount by the preinitiation application of the appropriate number of pulses.

it will be apparent that the embodiment shown is only exemplary and that various modifications can be made in construction and arrangement Within the scope of the invention as defined in the appended claim.

We claim:

In combination: an escape wheel mounted for springbiased rotation about a first pivot, a series of teeth spacedapart around the periphery of said wheel, each tooth being formed with substantially parallel leading and trailing edges, the leading edge of each tooth being shorter than the trailing edge so that the extremity of each tooth is at an angle with respect to either tooth edge, springbiased rotation of said wheel being in a direction from the trailing to the leading edge, a pallet mounted for rotation about a second pivot, a pallet actuating means adapted to drive said pallet, said pallet actuating means comprising, a magnetically sensitive armature having one end pivotally fixed and the other end free for pivotal movement, an electromagnet positioned adjacent said armature and adapted to attract the free end of said armature upon electrical pulsing of said electromagnet, a capacitor in circuit with said electromagnet, electronic circuit means including a battery and a diode adapted to discharge said capacitor at a predetermined repetitive rate, said electromagnct adapted to attract said free end of said armature at said predetermined repetitive rate in response to the pulsing of said capacitor, an arm depending from said pallet and extending to contact said free end of said armature so that said armature drives said arm in the direction of spring-biased rotation of said wheel upon discharge of said capacitor, upper and lower pins at the end of said pallet nearest said wheel, said upper pin located above an axis extending through said first and second pivots, said lower pin located below said axis, the radial distance from said second pivot to the upper pin being substantially greater than the radial distance from said second pivot to the lower pin, the upper pin initially engaging said leading edge of a tooth of said Wheel in the absence of an electrical pulse from said capacitor so as to prevent rotation of said wheel and urge said arm against said armature, said electromagnet receiving an electrical pulse from said capacitor only for a duration sufficient to cause said armature to drive said pallet a large enough distance to move said upper pin out of locking engagement with said leading edge of said tooth thereby freeing said wheel for rotative movement, said lower pin being positioned so that when said wheel rotates after being unlocked the extremity of a tooth pushes against said lower pin and causes said arm of said pallet to rotate in a direction opposite to that of wheel rotation, the rotation of the pallet thus caused again forcing said upper pin into locking engagement with the leading edge of a successive wheel tooth and at the same time restoring the arm of the pallet to its initial position in contact with said armature, the combined action of the pulsed actuating means and the pallet pins engaging the teeth of said wheel then continuing to intermittently rotate said Wheel one tooth distance for each electrical pulse applied to said electromagnet by said capacitor.

References Cited in the file of this patent UNITED STATES PATENTS 713,031 Westenholz Nov. 4, 1902 856,091 Ohlson June 4, 1907 967,304 Bailey Aug. 16, 1910 1,514,751 Wold Nov. 11, 1924 1,557,944 Reisbach Oct. 20, 1925 1,744,259 Carlson Jan. 21, 1930 1,795,013 Denman Mar. 3, 1931 2,097,066 Hoover Oct. 26, 1937 2,385,011 Lartz Sept. 18, 1945 2,647,362 Fidelman Aug. 4, 1953 2,679,722 Kohlhagen June 1, 1954 2,717,488 Linard Sept. 13, 1955 2,826,693 Resnik Nov. 11, 1958 

